A movable sinker apparatus has been conventionally used that includes, between knitting needles arranged on a needle bed in a weft knitting machine, a sinker displaced by a cam mechanism provided on a carriage such that the sinker is swingingly displaced using as a fulcrum the vicinity on a needle bed gap side of the needle bed, so that the front end portion of the sinker moves forward into the needle bed gap and is withdrawn from the needle bed gap (see Japanese Examined Patent Publication JP-B2 05-83657 (1993), for example). The carriage is provided with a cam for driving the sinkers.
The front end portion of the sinker moves back and forth with respect to the side of the needle bed gap in conjunction with the travel of the carriage, and thus the front end portion can press a knitting fabric, and can be withdrawn from the needle bed gap to prevent, for example, a mechanical contact with other components in the narrow needle bed gap. The force of a spring is also applied to the sinker of the movable sinker apparatus.
When a reaction force from a knitting yarn is greater than the force of the spring, there is room in which the front end portion moves backward from the needle bed gap, and thus too strong a tensile force can be prevented from being applied to the knitting yarn. However, during stitch determination in which the knitting needle is pulled in by a stitch cam, the front end portion of the sinker is regulated so as not to be moved by the cam backward from the needle bed gap. When the carriage moves away, a state is kept in which the front end portion of the sinker has moved forward into the needle bed gap by the force of the spring.
In this movable sinker apparatus, a knitting yarn receiving portion is formed as a recessed portion on the front end side. Thus, when knitting a knitting fabric, it is possible to prevent a knitting yarn of a previous loop from moving together with the knitting needle when the knitting needle moves forward into the needle bed gap, by catching the knitting yarn of the previous loop. It should be noted that a “previous loop” refers to a knitting stitch that is formed by catching a supplied knitting yarn with a hook of the knitting needle and that is still on the knitting needle.
A movable sinker is known that has upper and lower protruding portions (see Japanese Patent No. 2646317, for example). The upper protrusion of a sinker that is disclosed in Japanese Patent No. 2646317 has a function to press a previous loop such that the previous loop does not move upward together with a knitting needle when the knitting needle is moved forward into the needle bed gap.
As shown in descriptions “catching a course in which the knitting material is newly formed” in Paragraph [0010] and “fastening action of the cam 20 on the newest course of the knitting material” in Paragraph [0012], the lower protrusion acts on a previous loop, and has a function as in JP-B2 05-83657.
The movable sinker apparatus of JP-B2 05-83657 is swingingly displaced about a base portion of the sinker, and catches and presses down a knitting stitch of a previous loop with the knitting stitch receiving portion at the front end portion. Also in the configuration of the sinker as disclosed in Japanese Patent No. 2646317, the main function of the lower protrusion is to fasten and press down a knitting stitch of a previous loop as in JP-B2 05-83657.
More specifically, the knitting stitch receiving portion of JP-B2 05-83657 and the lower protrusion of Japanese Patent No. 2646317 prevent a previous loop from moving upward by pressing the previous loop, and also have a function to pull down a knitting fabric. However, a knitting fabric is not sufficiently pulled down depending on knitting conditions, and thus there is a request for a more reliable pulling-down function.